Chum salmon (Oncohynchus keta) and Northern Pike (Esox lucius) with Red Spots under Scales and Abrasions on Their Bellies

Observation by Bill Carter:

Chum salmon (Oncorhynchus keta) and northern pike (Esox Lucius) were caught in Buckland, AK, by Tim Gavin with red spots on their sides, under/between their scales. Mr. Gavin is a long-time fisherman (25+ years) and said he has never seen this before. He also reported multiple chum with abrasions between their pectoral fins. Mr. Gavin reported that he fishes relatively close downstream of the village and the water seems warmer than normal.

Jayde Ferguson, Fish Pathologist at Alaska Department of Fish and Game, writes:

The low mag photo of the whole fish looks like the red spots are hemorrhages, so likely a systemic infection such as bacterial septicemia. Warmer water can increase the reproductive rates of some pathogens while simultaneously stressing and reducing the immune system of the fish so these conditions are essentially like a two-fold factor for increasing the fish’s susceptibility to these infections.

Ted- do you have anything else to add?

Ted Meyers, State Fish Pathologist with the Alaska Department of Fish and Game, writes:

I think if you look at these lesions very closely they are foci of Saprolegnia fungus tinged with a small amount of hemorrhage. Fungus infections are common in returning salmon but more so in warmer waters where any small injury to the skin allows the fungus to invade. A bacterial septicemia also more common in warmer water could also be present to initiate the skin lesions.

Comments from LEO Editors:

Septicemia (used interchangeably with sepsis) is a condition resulting from the presence of harmful microorganisms in the blood/major tissues and the body’s immune response to their presence, which can potentially lead to organ malfunction, shock, and death. According to the Alaska Department of Fish and Game Diseases of Wild and Cultured Fish in Alaska, septicemia can be related to the presence of North American Viral Hemorrhagic Septicemia Virus (NA-VHSV), as well as Motile Aeromonas and Pseudomonas, bacterial pathogens of the genus Vibrio, and Phoma herbarum. Each infection may present different symptoms.